What is the best way to launch and retrieve from a high dock? (About 10 feet above the water) Is it ok to lower the sub by the tether? It seems to be rated for the weight but I’m guessing that would be less than ideal. Are people using some other tools like poles etc?
I tape 1/4 inch Poly Pro approx 6ft up from the ROV, My boat sits approx 4 ft up from the water surface, Than when you pull, you are not pulling directly on the tether as much, you are sharing the strain with the rope and the tether. What you see in the photo is slim tether, i used this system with the 8 conductor also.
I use good quality duct tape wrap every 8 to 10 inches, i use a oversize thimble at the termination point so that i can secure both the tether and the Poly pro to the Thimble.
You should be able to Go 10 ft with this system ok. Doing it this way does not seem to hinder the performance at all. The poly floats the tether up away from the ROV. Use good quality Duct tape, and tape under dry conditions.
Sorry about the photo being fuzzy, new camera i am still getting used to it.
Hope this helps
I’ve previously used a short length of rope tied across the back, and had a hook on the end of a long piece of rope with knots tied in it for grip, which then allowed lowering the vehicle without straining the tether. That said, catching it back onto the hook to raise it up again was a challenge sometimes.
The “best” approach depends on your definition. The most robust option would likely be having a crane/pulley mechanism of some sort, perhaps with a very strong electro-magnet for attachment, but that would be expensive and heavy, so may not be super feasible for you to transport/operate.
@Rontom’s suggestion of a rope/cord that’s somewhat integrated with/attached to the tether is less independent, but does still reduce the tether strain, especially if the rope is less extensible/shorter than the tether it’s alongside so that it takes most of the weight.
As I understand it we generally wouldn’t recommend lifting the ROV directly by the tether outside of emergencies, particularly because of the potential strain at the thimble, and any dynamic loading it may undergo if there are sudden drops/sharp pulls.
you can use an expandable Braided Cable Sleeve ( see below ) around your tether ( avoid tape or cable tie that can get your tether snag).
At the ROV end you can form a loop that can be attached to a solid point on the ROV thus avoid stresses on the cable thimble.
I described the process in a short tutorial here
Of course, you can reduce the length of the superimposed section, and increase the other part at your convenience !
You can also use a thicker sheath by using coreless ropes like this one :
Thanks everyone! These seem like great solutions. I’ll give it a try and let you know how it works once I get it in the water.